The present invention relates generally to a quick release chuck device configured for operation with a scroll saw blade, and specifically to a wedging blade clamp assembly having a release mechanism.
Conventional power saws are known to have blade holders using spring-loaded wedge members which urge captured balls against corresponding recesses or openings in blade shanks. Such prior art saw blade holders typically require the separate retraction of the clamping mechanism to permit insertion and removal of the saw blade. Other known blade retention assemblies further require the operator to grasp an outer surface of the retention mechanism and alternately push and/or pull the outer surface to insert and remove the blade. In addition, still other known blade clamping systems require the operator to twist and rotate the blade clamp into locked and open positions. These known arrangements are time consuming and cumbersome.
More specifically, U.S. Pat. No. 4,299,402 issued to Hoffman discloses a blade holder for a saber saw. The blade provided is configured with a pair of opposed side marginal edges with a notch or recess in at least one side marginal edge near the rear side of the blade. Hoffinan further discloses a saber saw blade holder having a pair of biased balls that engage the corresponding notches or recesses in the blade. The balls are urged against the blade by a retractable, spring-loaded barrel with an internal wedge-shaped cavity.
A disadvantage in Hoffman is that to remove the saw blade, the barrel must be manually grasped and rotated in a clockwise or rightward direction to pull the biased balls away from their engagement with the recesses or notches in the rear end of the saw blade. A reverse rotating motion in a counter-clockwise or leftward direction is required to re-engage the biasing balls with the notches or recesses of the blade.
A further disadvantage in Hoffman is that the saw blade must be specifically manufactured with specially shaped notches or recesses to engage the balls of the spring-loaded barrel. A third disadvantage is that Hoffman does not disclose or suggest a one-handed insertion mechanism for the saw blade.
U.S. Pat. No. 5,573,255 issued to Salpaka discloses a quick release chuck device for holding a saw blade. The saw blade has a rectangular shank portion and a detente recess defined in at least one of its side edges. The Salpaka device includes a body member having an internal longitudinal bore. A transverse radial bore is in communication with the longitudinal bore through a short side of the longitudinal bore. An engaging device, such as a detente ball, is positioned in the radial bore and is radially movable within the radial bore so that at least a portion of it extends into the longitudinal bore to contact an edge of the saw blade in a locking position of the chuck device.
A spring-biased outer sleeve is further disposed about a portion of the body member. This outer sleeve is movable longitudinally with respect to the body member between a locked position and a released position.
A disadvantage in Salpaka is that a separate action is required of an operator to grasp the outer sleeve and pull or push the outer sleeve longitudinally against the biasing force of the spring mechanism to insert or release the saw blade. Another disadvantage is that Salpaka does not disclose or suggest a one-handed saw blade insertion mechanism of the present blade holding assembly.
U.S. Pat. No. 5,575,071 issued to Phillips et al., discloses a clamping system for attaching a saw blade to a blade carrier of a reciprocating saw. The system includes a clamp member having a hollow interior and a tubular body. The clamp member is disposed on a free end of a blade carrier which includes a longitudinal slot for receiving a shank of a saw blade. In a side wall of the blade carrier there is an aperture. A ball is received within this aperture and moves freely therein. The clamp member has an inner surface which includes an eccentric groove. A camming surface which engages the ball is defined by the eccentric groove. A spring is attached to the blade carrier and the clamp member to bias the clamp member toward a first or locked position.
A disadvantage in Phillips is that the clamp member must be separately rotated to a first locking position whereby the ball engages an opening in the shank of a saw blade to hold the blade in place. A further disadvantage is that the clamp member must be rotated to a second unlocking position to disengage the ball from the aperture in the blade to allow for blade removal.
Another disadvantage, as in the case with Hoffinan, is that Phillips requires saw blades manufactured with an aperture to engage the ball.
In using blade retaining mechanisms in a scroll saw, operators desire a convenient one-handed insertion of the blade into the holder without the separate retraction of the holder or the use of a separate tool. Operators further desire a faster and easier quick change mechanism for a scroll saw blade. Improvement in blade changing is also needed by those with little hand strength or other hand problems such as carpal tunnel syndrome.
Thus, there is a need for a blade retention mechanism whereby a blade may be easily inserted with one hand into the holder, merely by thrusting a part of the retention mechanism upward with sufficient force to overcome a downward force of a biased spring. Once inserted, the blade will not come out unless released, due to a wedging clamping action of at least one locking element against the blade.
Therefore, it is an object of the present invention to provide an improved blade retention mechanism allowing the one-handed insertion of the blade into the holder without the separate retraction of the holder.
A further object of the present invention is to provide an improved blade retention mechanism featuring faster and easier blade changing for a scroll saw blade even for operators with decreased hand strength.
The above identified objects are met or exceeded by the present wedging blade clamp for a scroll saw. An improved quick release chuck device is provided that allows the one-handed insertion of a blade into a holder without separate retraction of the blade holder. A blade may be inserted into the holder merely by thrusting the blade into the holder with sufficient force to overcome a biasing force exerted by a biasing element. Once inserted, the blade will not come out unless released, due to a wedging clamping action of at least one locking element against the blade. A release member acts on the retention mechanism to release the biasing force and allow removal of the blade. In another embodiment of the present invention, the retention mechanism is directly acted upon to release the biasing force and allow removal of the blade.
More specifically, the present invention provides a wedging clamp assembly for retaining a saw blade. A housing is included having a vertical cavity. The vertical cavity has a top end and a bottom end tapered with respect to the top end. The bottom end of the vertical cavity has a saw blade passageway that extends through a bottom end of the housing.
Furthermore, a saw blade retention mechanism is disposed within the vertical cavity and includes a piston disposed within the cavity. The saw blade retention mechanism is configured for lockingly retaining the saw blade upon insertion into the passageway, causing the piston to be biased against the bottom end of the vertical cavity.
The saw blade retention mechanism further includes at least one locking element that is disposed in the vertical cavity for engaging the cavity""s bottom tapered end and for exerting a wedging clamping force on the saw blade. The wedging clamping force renders the saw blade immobile relative to the housing.
The saw blade retention mechanism is configured for releasing the blade when the biasing force on the piston is overcome by an opposing force applied to the piston, thus, causing the wedging clamping force on the saw blade to be released. This action allows for the one-handed insertion of the blade into the clamping assembly without the separate retraction of the holder. Thus, a quick change of a scroll saw blade is provided, even for operators with decreased hand strength.